package main
import (
	"fmt"
	"strings"
)
func main() {
	var phone string
	phone = "13412345678"
	old := ""
	for k, v := range phone{
		if k >=3 && k <=6{
			old = old + string(v)
		}
	}
	phone = strings.Replace(phone,old,"****",-1)
	fmt.Println(phone)  //134****5678
}
